Protective Effects Of SE And Zeolite On Broilers Exposed To Aflatoxin B₁

Aflatoxin contamination is a common problem in livestock industry, it would cause adverse effects on animal productive and reproductive performance, and residues of aflatoxin in muscle and tissue can further cause harmness to the human body. One reason for aflatoxin induced body damage is that it could induce the generation of ROS, which could cause oxidative stress in body. It would induce body damage when oxidant stress is beyond body antioxidative activity. As a mycotoxin adsorbent, zeolite have been researched for a long time, and its action mechanism is identified by researchers; selenium(Se) is one of the necessary nutrition element and an important antioxidant, as an essential composition of a number of antioxidative enzymes and detoxifying enzymes Ⅱ, Se plays a great role in antioxidative stress reaction. There are many reports on Se detoxication, however, the mechanism is not clear. Studies showed that, Se deficiency induced cytosolic Nrf2 decoupling and transfering into nucleus, and initiating the expression of downstream phase Ⅱ enzymes and antioxidant enzyme gene regulated by nucleus Nrf2, therefore, we suspected that protective effects of Se in attenuating toxicity of aflatoxin B1 may be relevant to Nrf2 related antioxidant pathway. Results are as follows:1. Protective effects of Se and zeolite in aflatoxin B1 induced hepatic oxidative stress in broilersTo investigate the protective effects of Se and zeolite on aflatoxin B1 (AFB1) exposed broilers and its probable mechanism, one hundred and fifty one-day-old broilers were randomly allotted to 5 groups and treated for 42 days as follows:A. control (basal diet alone), B. AFB1 group (AFB1 at 100 μg/kg of feed), C. Zeo group (AFB1 at 100 μg/kg of feed plus 3% zeolite), D. Se group (AFB1 at 100 μg/kg of feed plus 0.3 mg/kg Se), E.Zeo+Se group(AFB1 at 100 μg/kg of feed plus 3% zeolite and 0.3 mg/kg Se). The results showed that:Compared with control, the broilers in AFB1 group had a lower liver organ weight (P<0.05), serum glutamic pyruvic transaminase (GPT) activity were significantly increased (P<0.05). The generation of maleic dialdehyde (MDA) and H2O2 upon AFB1 treatment were higher than control (P<0.05), but total superoxide dismutase (T-SOD)、 glutathione (GSH) and glutathione peroxidase (GSH-Px) content were significantly decreased (P<0.05). Compared with AFB1 group, liver function index were improved by Se and zeolite addition. Liver GSH-Px and T-SOD activity returned to control and were significantly increased(P<0.05). In concluded:Se and zeolite could attenuate hepatic oxidative stress induced by AFB1, increased antioxidant ability in AFB1 exposed broilers, however, the combination effects of Se and zeolite were not better than they were used alone.2. Protective effects of Se and zeolite in aflatoxin B1 induced testicular oxidative stress in broilersAnimal treatment was as previous study. The results showed that:effects of AFB1、Se、 zeolite and their combination on testicular weight and organ index had no significant difference (P>0.05). Activity of CAT、GSH and GSH-Px were significantly decreased(P<0.05) while H2O2 (P>0.05) and MDA(P<0.05) level increased in AFB1 group. Compared with AFB1 group, GSH level of zeolite group returned to control levels, other antioxidative indexes in zeolite, Se and their combination group were improved but not significant (P>0.05). Testicular morphology of control group was normal while testes of AFB1 and Zeo group became smaller than control; histological sections showed that the contorted seminiferous tubules in control was intact, stromal cells and spermatogonia cells were clear, cell nucleus were in the middle of cells, gap among seminiferous tubules was wider, Testicular morphology of other groups were normal, too. In conclude, Se and zeolite could alleviate broiler tesicular oxidative stress induced by AFB1, nevertheless, AFB1 didn’t cause substantial injury to the testicles from the morphological results.3. Possible mechanism of Se in attenuating toxicity of AFB1 in liver and testis of broilerTo investigate the possible mechanism of Se in attenuating toxicity of AFB1 in liver and testis of broiler, we have measured the expression of Nrf2 and caspase-3 by immunohistochemistry and western blotting assay in cell nucleus, ninety one-day-old broilers were randomly allotted to 3 groups (3 replicates per treatment and 10 birds per pen) and treated for 42 days as follows:basal diet alone (control), AFB1 at 100 μg/kg of feed (AFB1 group), AFB1 at 100 μg/kg of feed plus 0.3 mg/kg Se (Se group). Results showed: expression of Nrf2 protein was increasing in hepatic and testicular nucleus, caspase-3, an apoptosis factor were only detected in AFB1 group by western blotting assay. Se addition could reduce the expression of Nrf2. In conclude:protective effects of Se in attenuating toxicity of aflatoxin B1 may be relevant to Nrf2 related antioxidant pathway.